Melanotan II

What it is

Melanotan II is a synthetic melanocortin peptide developed from alpha-melanocyte-stimulating hormone research. It is structurally related to melanotan I and bremelanotide, but it is not the same as either FDA-approved afamelanotide or FDA-approved bremelanotide^{[1 ,12 ]}. Melanotan II has been studied for pigmentation and sexual-function effects, and it is widely marketed online as an injectable or nasal tanning product.

Chemical structure

Melanotan II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2 and molecular formula C50H69N15O9^{[1 ]}. It activates melanocortin pathways involved in pigmentation and sexual-function physiology, but no FDA-approved Melanotan II product exists in the United States^{[1 –5 ]}.

Mechanism

The peptide acts through melanocortin receptor biology. Melanocortin receptor activation can increase melanin production in skin and can also affect central pathways involved in sexual arousal and appetite^{[1 ,8 ]}. This broad receptor activity helps explain why Melanotan II is associated with both tanning and sexual side effects, including erections in early clinical studies^{[8 ]}.

Melanotan II is not an approved tanning aid. FDA-approved sunless tanning products, such as topical products using approved color additives, are regulated differently from systemic drugs that change pigmentation through receptor activation^{[13 –14 ]}. A peptide injected under the skin or inhaled intranasally to cause physiologic pigmentation is not a cosmetic merely because the desired outcome is cosmetic.

When used in public or gray-market settings, Melanotan II is usually obtained as a lyophilized powder, nasal spray, or premixed injection. These products are not FDA-approved, are not subject to FDA premarket review for safety, effectiveness, or manufacturing quality, and may vary in identity, strength, purity, sterility, or labeling^{[2 –7 ]}.

Regulatory status

Melanotan II is not FDA-approved for any indication. No FDA-approved drug product containing Melanotan II was identified in FDA approval materials reviewed for this draft^{[2 –6 ]}.

April 2026 503A removal — procedural, not authorization

FDA’s April 22, 2026 503A update states that “Melanotan II” was removed from Category 2 because nominations were withdrawn. FDA also stated that it intends to consult the Pharmacy Compounding Advisory Committee before the end of February 2027 regarding possible inclusion of Melanotan II on the 503A bulks list^{[2 ]}. Removal from Category 2 is not FDA approval and is not a final finding that Melanotan II may be routinely compounded^{[2 –3 ]}.

Under section 503A, a bulk drug substance generally must have an applicable USP/NF monograph, be a component of an FDA-approved drug product when no monograph exists, or appear on the FDA 503A bulks list^{[3 ]}. Melanotan II is not listed in Category 1 in the April 22, 2026 document and was not identified on the 503A bulks list reviewed for this draft^{[2 –3 ]}.

503B and FDA safety-risk listing

For 503B outsourcing facilities, FDA states that bulk substances may be used only if the substance appears on the 503B bulks list or the compounded drug appears on the shortage list at the relevant time^{[4 ]}. Melanotan II was not identified on the 503B bulks list reviewed for this draft^{[5 ]}.

FDA’s safety-risk page lists Melanotan II among withdrawn nominated substances and states that compounded drugs containing Melanotan II may pose immunogenicity risks related to aggregation or peptide-related impurities. FDA also notes that published case reports discuss serious adverse events including melanoma, posterior reversible encephalopathy syndrome, sympathomimetic toxidrome, and priapism^{[6 ]}.

Controlled-substance and international warnings

Melanotan II was not identified in the federal controlled-substance schedules in 21 CFR Part 1308 as reviewed for this draft^{[7 ]}. International regulators have issued public warnings. Ireland’s HPRA states that Melanotan 2 is not authorized by HPRA or any medicines regulator to treat any condition, including changing skin color^{[9 ]}. Australia’s TGA warns that melanotan products are illegally promoted online and can cause serious side effects^{[10 ]}.

Date of last regulatory verification: May 5, 2026.

Research summary

Human clinical research on Melanotan II is limited and old compared with modern approval standards. In a double-blind, placebo-controlled crossover study, Wessells and colleagues evaluated Melanotan II in 10 men with psychogenic erectile dysfunction using RigiScan monitoring over six hours^{[8 ]}. Clinically apparent erections occurred in 8 of 10 treated men, and transient nausea, stretching, yawning, and decreased appetite occurred more often after Melanotan II than placebo^{[8 ]}. This small study does not establish Melanotan II as an approved erectile dysfunction treatment.

Pigmentation and tanning context

Pigmentation effects are biologically plausible because Melanotan II stimulates melanocortin pathways involved in melanin production^{[1 ,10 ]}. However, online tanning use is not equivalent to a controlled dermatologic therapy. Tanning products sold as Melanotan II often depend on concurrent ultraviolet exposure to deepen pigmentation, and FDA states that UV exposure increases risks of skin cancer, burns, premature skin aging, and eye damage^{[13 –14 ]}.

Safety signals dominate the literature

Regulatory and safety literature is more prominent than modern clinical efficacy research. FDA specifically lists serious published adverse-event case reports in connection with Melanotan II-containing compounded drugs, including melanoma, posterior reversible encephalopathy syndrome, sympathomimetic toxidrome, and priapism^{[6 ]}. HPRA and TGA warnings similarly emphasize unauthorized products, online sales, nasal sprays or injectable powders, and serious health risks^{[9 –10 ]}.

Distinct from bremelanotide (Vyleesi)

Melanotan II is sometimes confused with bremelanotide, also known as PT-141, because both are melanocortin agonist peptides and share related sequence motifs^{[1 ,12 ]}. Bremelanotide is FDA-approved as Vyleesi for a narrow indication in premenopausal women with acquired, generalized hypoactive sexual desire disorder; Melanotan II is not FDA-approved for tanning, sexual function, weight loss, or any other use^{[11 –12 ]}.

Overall, the evidence base does not support medical or cosmetic claims for consumer Melanotan II use. The most defensible editorial position is that Melanotan II is an unapproved melanocortin peptide with limited early human sexual-function data, public-health warnings for tanning use, and documented serious safety concerns.

Public discourse

The Therapeutic Goods Administration, Australia’s medicines regulator, warned against nasal, injectable, and ingestible melanotan products sold online^{[10 ]}.

The Health Products Regulatory Authority (HPRA), Ireland’s medicines regulator, warned about Melanotan 2 products sold as injectable powders, nasal sprays, or drops^{[9 ]}.

Anand N. Rajpara, MD, dermatologist at the University of Kansas Health System, explained the regulatory and physiologic concerns with tanning products containing Melanotan II^{[15 ]}.

David Carter, MHRA medicines borderline section, warned against using unlicensed tanning products to obtain a tan^{[16 ]}.

Public discourse reflects the views of the speakers cited and does not represent medical advice or the editorial position of ProPeptideGuide.

Side effects and safety

Melanotan II has no FDA-approved prescribing information, so there is no FDA-reviewed label establishing contraindications, common adverse reactions, pregnancy safety, drug interactions, or monitoring requirements^{[2 –6 ]}.

In the small erectile dysfunction crossover study, transient side effects included nausea, stretching, yawning, and decreased appetite^{[8 ]}. FDA’s safety-risk summary cites published case reports involving more serious events, including melanoma, posterior reversible encephalopathy syndrome, sympathomimetic toxidrome, and priapism^{[6 ]}.

Pigmentation-related concerns

Pigmentation-related concerns are central. Because Melanotan II affects melanocortin signaling and melanin production, changes in moles, freckles, and pigmentation may complicate skin-cancer surveillance^{[6 ,9 –10 ]}. TGA specifically warns of increased moles and freckles, kidney dysfunction, and swelling of the brain in connection with Melanotan II^{[10 ]}.

Gray-market product quality

Gray-market products add independent risks. Nasal sprays, powders, and injections sold online may be contaminated, mislabeled, nonsterile, or inaccurately concentrated. FDA’s compounding concerns include immunogenicity and peptide-related impurity risks^{[6 ]}.

Long-term safety data are insufficient. Melanotan II should not be treated as a benign cosmetic product merely because it is marketed for tanning.

Available through

Melanotan II is not currently available through FDA-compliant prescription or compounding channels in the United States as of 2026-05-05^{[2 –6 ]}. It is not FDA-approved, is not on the 503A or 503B bulks lists, and is not an FDA-compliant tanning, sexual-function, or weight-loss product.

ProPeptideGuide does not link to or endorse grey-market vendors, research-chemical sellers, online peptide shops, or clinics advertising Melanotan II for tanning, sexual function, weight loss, or any other use.